The embodiments discussed herein relate to a network element for allocating at least one payload data connection to at least one multiplex connection which is provided between a first network element and a second network element.
For the purpose of transmitting voice data via a mobile communication system or mobile radio system, use is increasingly being made of packet-oriented data transmission methods in which, depending on the transmission protocol that is used in each case, data fields having different sizes are provided for transmitting the compressed voice data. Transmission protocols that are generally used include “Layer 2” transmission protocols such as e.g. the Ethernet protocol, as well as the Internet Protocol (IP), the “User Datagram Protocol” (UDP) (RFC 768), the “Realtime Transport Protocol” (RTP) (RFC 3550), and in many cases also the “Iu Framing Protocol” (IuFP) (3GPP TS 29.415).
For example, in the so-called CS domain of the “Core Network” of a third-generation mobile radio system (3GPP), a so-called “Nb” data connection is established for data transmission e.g. between a so-called Media Gateway unit (MGW) and/or a “Mobile Switching Center” (MSC). The voice or multimedia data to be transmitted is compressed, e.g. by an “Adaptive Multi-Rate” (AMR) voice encoding unit, and the compressed voice data is then transmitted via the “Iu Framing Protocol” (IuFP) (3GPP TS 29.415) or the RTP, UDP or IP protocol (cf. standard 3GPP TS 29.414).
The data fields of the relevant transmission protocols, i.e. the relevant “headers”, are together often significantly larger than the data, e.g. compressed voice data, which is transmitted therein. For example, the data field of an IP packet has a size of 20 bytes (IP Version 4.0) or 40 bytes (IP Version 6.0). The data fields of the UDP protocol have a size of 8 bytes, whereas the data fields of the RTP protocol comprise 16 bytes and those of the IuFP protocol comprise 4 bytes. By contrast, the data which is compressed by the AMR voice encoding unit has a size of 35 bytes in the “12.2 kHz” mode or a size of 5 bytes in the “Silence Indication” (SID) mode which is used between voice pauses.
A plurality of payload data connections, e.g. telephone connections, are usually transmitted concurrently between at least two Mobile Switching Centers or two Media Gateway units, e.g. in accordance with the standard for the so-called NB interface. In the same manner as the Nb interface, the data transmission can take place via the “lu” interface which is likewise provided in a 3GPP mobile radio system and exists between a Media Gateway unit or a Mobile Switching Center and a so-called “Radio Network Controller” (RNC) unit (cf. 3GPP TS 25.414 and 25.415).
The currently existing standards provide for an individual physically separate data connection, this being realized in accordance with the relevant transmission protocol for an IP/UDP/RTP data connection, to be established via the Nb or Iu interface for each payload data connection that is to be transmitted, e.g. for a telephone call, and for the data packets, these being constructed in accordance with the relevant IP, UDP and RTP transmission protocol, to be transmitted via the data connection.
In the context of both the Nb interface and the Iu interface, the IP, UDP and RTP protocol is terminated in each case at the delimiting Media Gateway unit and the delimiting Mobile Switching Center or the delimiting RNC, i.e. the data fields of the individual data packets that are transmitted via the Nb or Iu data connection correspond to some extent at least and are read out and further processed in the cited units following the transmission. By contrast, the data fields of data packets that are realized in accordance with the IuFP protocol are routed through the relevant Media Gateway unit or Mobile Switching Center unchanged.
Furthermore, a multiplicity of multiplexing technologies, via which data of a plurality of payload data connections is transmitted almost simultaneously by a multiplexed data connection, are known in the field of transmission technology. Such data connections, being provided for the purpose of transmitting a plurality of payload data connections or telephone connections, are subsequently designated as multiplexed connections.
At the Nb or Iu interface, data of a plurality of payload data connections is advantageously transmitted together within a multiplexed connection which is preferably transported by the IP/UDP/RTP protocols. Data of a plurality of payload data connections, preferably with individual IuFP header and individual payload data such as e.g. compressed voice data in each case, could thus be contained in one IP packet which contains in each case only one IP, UDP and RTP header. As a result, the required bandwidth for the transport could be significantly reduced. This possibility is not yet described in the standard, however.
For the purpose of establishing a payload data connection via an Nb data connection, provision is made for the so-called “BICC IP Bearer Control Protocol” (IPBCP) (ITU-T Q.1970), which itself uses the so-called “Session Description Protocol” (SDP) (IETF RFC 2327) (cf. 3GPP TS 29.414). For the purpose of establishing a payload data connection between a first and second Media Gateway unit, the IPBCP protocol provides for the transmission of an “IPBCP Request Message” from the first to the second Media Gateway unit. This message is answered by the second Media Gateway unit by an “IPBCP Response Message”. Using the cited IPBCP messages, the first and second Media Gateway units exchange their respective IP addresses and UDP port numbers, knowledge of which is required for the exchange of data between the first and second Media Gateway units. The IPBCP messages are transmitted transparently by the so-called BICC signaling protocol (ITU-T Q.1902.1-5).